This invention relates generally to electrical connectors of the insulation-opening or displacement type and, more particularly, to electrical connectors having contacts with displaceable or flexible sidewalls which hold and support the contacts in the cavities of the connectors in which the contacts are mounted.
Electrical connectors having insulation-piercing contacts are well known in the art and have met with considerable commercial success. Typical examples of such prior art connectors are illustrated in U.S. Pat. Nos. 3,867,005 and 3,926,498. The contacts employed in these connectors generally include terminal elements which sever or cut through the insulation and establish an electrical connection with the conductor without the need for any stripping or soldering operation. The insulation-piercing terminal elements typically include opposed cutting edges that sever and penetrate the insulation and serve as wiping surfaces, in some configurations, to make the necessary electrical connection with the conductor. The insulation-piercing terminal, therefore, serves both to sever the insulation and establish an electrical connection with the conductor. The disclosures of these aforementioned prior art patents describing the specific structural details of these prior art connectors, together with their specific manner of use, are incorporated herein by reference.
As mentioned above, the prior art insulation-piercing connectors have met with considerable commercial success. Nevertheless, certain problems arising in the fabrication of the miniaturized electrical components used in these connectors have resulted in designs which comprise the optimum performance characteristics which could otherwise be attained. For example, since the insulation-piercing contacts may be most economically manufactured by press and stamping operations, it is necessary to use sheet metal stock which is easily formable. Such sheet metal stock has a tensile strength which is less than that generally considered optimal for withstanding the forces encountered in the connection operation. Accordingly, certain of the structural components of prior art contacts which comprise the insulation-piercing terminal elements may be, in some instances, deformed or bent in the connecting operation to the point where proper electrical connection may be adversely affected. In addition, because of tolerance ranges required to minimize the cost of manufacture and to facilitate assembly, a small space often exists between the sidewalls of the contact and the lateral surfaces of the insert cavity in which the contact is mounted. Thus, the sidewalls have little or no lateral support and are susceptible to an outward lateral V-type deformation during the connecting operation, thereby further jeopardizing the quality of the electrical connection obtained. This deformation associcated with prior art connectors is characterized as "V-type" due to the fact that the terminal sidewalls spread only at their upper portions during the connecting operation. Thus, the terminal has a slight V-shape or upwardly diverging configuration when viewed in cross-section. This is undesirable since the terminated conductor has a tendency, in time, to lift or loosen from the contact terminal and may also result in a lack of uniform termination force on the conductor, and particularly on the individual strands of stranded core conductors.
Another problem associated with prior art insulation-piercing connectors is that they are not well suited to stranded core conductors. Oftentime, individual strands of such conductors snag on, or are severed by, the opposed cutting edges of the insulation-piercing terminal element. In addition, cold flow of the insulation subsequent to termination can result in movement of the individual strands and changes in the engagement area and force between the conductor and the sidewalls of the contact. Therefore, when utilizing stranded core conductors, the quality of both the electrical and mechanical connection attained with prior art connectors may be seriously impaired.